The smoking of parents and siblings is statistically associated with the smoking of younger children in the family. The specific mechanisms by which families impact on smoking decisions remain to be elucidated. The proposed research is a partly exploratory, partly hypothesis testing investigation of the role of the family in the acquisition of adolescent smoking behavior. There are three major aims. One is to determine the extent of parent and sibling influence on adolescent smoking decisions and to evaluate the relative strength of these sources compared to peer influence. The second major aim to delineate the specific mechanisms or psychological processes by which families influence their children's smoking decisions. Parent and sibling smoking status, expectations, attitudes, communication, rule setting, and consequences will be studied. The third aim is to obtain, for the first time, direct observation data on smoking-related family interactions and to compare these findings to those obtained from questionnaire and interview data. One thousand families will be recruited to participate in the study. Parents and all adolescents between the ages of 11 and 15 will complete extensive parallel questionnaires under bogus pipeline conditions to increase the validity of their responses. Sixty percent of the families will contain one or more smoking parents. A subsample of 150 intact families will be selected for more intensive investigation. Parents and a target child will be instruncted to solve standardized and family-specific problems related to tobacco and other drug use. The problem-solving sessions will be videotaped for later coding. Intensive interviews will be conducted with the same subsample to obtain an historical restructuring of initial smoking pressures and trials and parents' attempts to deal with these events. The entire sample will be followed up every 3 months with brief systematic telephone interviews and annual questionnaires for a 2-year period. Problem-solving and interview data will be collected at the end of the first follow-up period. Both cross-sectional and longitudinal analyses will be conducted. Confirmatory causal modeling using LISREL VI procedures will be carried out on the questionnaire data to test specific hypotheses about family influences on a target child's smoking behavior. Similarly, hypotheses about parent influences will be tested on the smoking behavior of all adolescents in the family. Discrepancies between parent and child responses will be examined. Problem-solving and interview data will also be analyzed.